Two Dimensional Arrays (Array of Arrays)

 //Seating Arrangement for 20 Seats
 int arrSeating[][] = new int[4][5];

 //No of Items Produced in Hr By Days in Month
 int arrProdHrByDaysInMonth[][] = new int[30][24];

Two Dimensional Arrays(Array of Arrays of Arrays)

 //No of Items Produced in Hr By Days in Month by Month
 int arrProdHrByDaysInMonth[][][] = new int[12][30][24];

Jagged Arrays
array of arrays such that member arrays can be of different sizes

Looping through ArrayList

         	//Iterate over Collection
		for (Iterator iterator = arrNames.iterator(); iterator.hasNext();) {
			String object = (String) iterator.next();
			System.out.println(object);
		}			
		
		//Iterate over array or Collection
		for (String string : arrNames) {
			System.out.println(string);
		}		
		
		//Iterate over array 
		for (int i = 0; i < arrNames.size(); i++) {
			System.out.println(arrNames.get(i));
		}
		
		//Iterate over array using Temporary Variable
		for (int i = 0; i < arrNames.size(); i++) {
			String string = arrNames.get(i);
			System.out.println(string);
		}

Which one of the Above method is Faster?
All the methods are of same speed since the Traditional for loop uses Iterator inside.The performance difference is noted when there is change in data structure while doing random access like linkedlist is slower than arraylist when you use a traditional for loop since to traverse a 6th element in list it should start from all again

When there is a sorted Array and you should do a search in the sorted array then using BinarySearch is faster than Linear Search